Long-Term Follow-Up and Risk of Cancer Death After Radiation for Post-Prostatectomy Rising Prostate-Specific Antigen

Abstract

The results of salvage radiation therapy for rising prostate-specific antigen (PSA) levels after radical prostatectomy appear favorable, but the ultimate outcome is uncertain, given the relatively short follow-up in most studies. We report on a group of patients at a median follow-up of 13.9 years after salvage radiation therapy. From 1990 to 1995, 92 patients were referred postoperatively for radiation for a rising PSA level. PSA level at the time of referral ranged from 0.1 to 30.5 ng/ml (median, 1.5 ng/ml). The median time from surgery to radiation was 2.1 years (range,, 0.3-7.4 years). Radiation was directed to the prostatic fossa only with a median dose of 6,500 cGy (range, 6,000-7,000 cGy). Eighty-five patients experienced a PSA drop after radiation, as predicted by Gleason score and PSA level at the start of radiation. Five- and 10-year biochemical failure free survival (BFFS) was 35% and 26%, respectively, and overall survival was 86% and 67%, respectively. Median survival was 12.0 years, and median BFF was 2.3 years. The presurgery PSA level was not predictive, but the PSA level at the start of radiation predicted a response. Patients with Gleason 8 to 9 cancers had a significantly higher progression rate than those with lower Gleason scores. There were no significant differences in outcomes based on pathology findings (none vs. positive margins vs. positive seminal vesicles). Overall, 22 (24%) patients died directly from prostate cancer, resulting in a 10-year cancer-specific survival rate of 82%. Multivariate analysis risk factors for dying of cancer were Gleason's score (8 to 9) and PSA at the start of radiation therapy (>1.0 ng/ml). Patients have a good response to salvage radiation therapy. A small but durable subgroup appears to have permanent control. In those for whom therapy fails, radiation delays the need for other salvage therapy, indicating at least a transient benefit to most patients.